| Official Name: | Castletownshend |
| Native Name: | Irish: Baile an Chaisleáin |
| Native Name Lang: | ga |
| Settlement Type: | Village |
| Pushpin Map: | Ireland |
| Pushpin Label Position: | bottom |
| Pushpin Map Caption: | Location in Ireland |
| Subdivision Type: | Country |
| Subdivision Name: | Ireland |
| Subdivision Type1: | Province |
| Subdivision Name1: | Munster |
| Subdivision Type2: | County |
| Subdivision Name2: | County Cork |
| Unit Pref: | Imperial |
| Population As Of: | 2016 |
| Population Footnotes: | [1] |
| Population Total: | 196 |
| Utc Offset1: | +0 |
| Timezone1 Dst: | IST (WEST) |
| Utc Offset1 Dst: | -1 |
| Coordinates: | 51.5333°N -20°W |
| Blank Name: | Irish Grid Reference |
Castletownshend (literally "town of the castle")[2] is a village about south-east of Skibbereen, in County Cork, Ireland. The village developed around a small 17th-century castle built by Richard Townsend, whose descendants still reside there.
The main street of the town, lined with large homes from the 18th century, runs down a sharply sloped hill leading to Castlehaven Harbour and the castle. The Church of St Barrahane, built in 1826, overlooks the town.
Castletownsend was the home of Edith Anna Œnone Somerville, one half of the writing duo Somerville and Ross, who together authored the Irish RM series of humorous novels on Irish life in the early 1900s. The two met each other for the first time in Castle Townshend in 1886.
Sir Patrick Buckley (1841–1896) was born near the village in the townland of Gortbrack.